The contracts can't be enforced so why have one.
It takes effort to enforce a contract. Small claims court, maybe a lawyer. It may not be worth the effort to enforce the contract, but the contract at least tells you what the dog is supposed to be, what the seller promises to do if there is a problem. If I were working with a stranger, as either the buyer or seller, I would prefer the agreement be in ink on paper just to avoid confusion. There are a lot of things I don't know, but I am fairly sure that when things go to court, written documents trump a handshake every time.
You hit on the problem Bojack, there never is any documentation on the net.
The contract is your documentation, along with vet reports, photos, reports from quality breeders.
Does the original posters state have a puppy lemon law. MN does, and would give some recourse even with out a contract. Some states have laws that effect hobby breeders and apply to any sale of pups or even cats.
http://www.malteseonly.com/lemon.html lists some states puppy lemon laws.
It's good that you feel better with a contract but I wouldn't because of what I said, you can't enforce it or you will spend several thousand dollars trying to. And for what?
I don't offer contracts and I wouldn't buy a pup with one. I do offer a verbal contract and that is as good as it gets, that and a handshake. I try very hard to not deal with people who need more.